Rolling mill



Nov. 28, 1944- c. E. GROSSER ETIAL ROLLING MILL Filed Nov. "23, 1940 6 Sheets-Sheet l grass 01m 4 M3011 aria Nov. 28', 1 944.-

' C.-E. GRossE'R ET AL' ROLLING MILL Filed NOV. 23, 1940 6 sheets-sheet 2 N -2 9 I c. E. GROSSER ET'AL, Y 2,363,585

ROLLING MILL Filed Nov. 23, L940 6 Sheets-Sheet 3 C. GROSSER ET AL ROLLING MILL Nov. 28, 1944.

Filed No v. 25, 1940 e Sheets-Sheet 4 Nov. 28, 1944. 5 GROSSER ET AL 2,363,585

ROLLING MILL Filed NOV.' 23, 1940 6 Sheets-Sheet 5 Nov. 28, 1944. c. E. GROSSER ET AL 2,363,585

ROLLING MILL Filed Nov. 23, 1940 6 Sheets-Sheet 6 Patented Nov. 1944 ROLLING MILL ChristianE. Grosser, Cambridge, Mass., and Herman A. Bondeson, Providence, R. 1., assignors to Standard Machinery Company, Cranston,

R. I., a corporation of Rhode Island I Application November23, 1940, Serial No. 366,864

18 Claims.

The present invention relates to improvements in rolling mills and more particularly to a methd of driving the reduction rolls and individual hydraulic driving means for each of the units 1 of tandem mills.

It has heretofore been proposed to provide hydraulic drives for the plurality of units of a rolling mill but in such previous drives the speed l of the reduction rolls or the speed ratio between these sets of reduction rolls is maintained constant while the torque of the rolls is permitted to .vary. Such prior artdrives usually comprise a constant displacement fluid motor for driving the reduction rolls and the speed is determined by the amount of motive fluid supplied thereto. The'motive fluid for the motor is usually supplied by a pump andthe-speed of themotor is controlled by adjusting the displacement of the pump. Thus, the driving motors for a plurality of sets of reduction rolls apply from a minimum to a maximum of torque to the work to maintain the particular speed ratio between successive sets of reduction rolls. Adjustment of the various pumps to coordinate the speed of the various rolling units is very difiicult as any stretch or slack in the stock between successive sets of reduction rolls, due to discrepancies in the speed a rolling mill of the type indicated having a hydraulic drive for operating the take-up reel to apply aconstant tension on the rolled stock as it is wound on the reel.

Another object of the invention is to provide a rolling mill of the type indicated having hydraulic operating means for relatively traversing the take-up reel and stock to deposit the stock in superimposed layers of adjacent coils on the reel.

Still another object of the invention is to provide hydraulic drives, of the type indicated which are of comparatively simple construction to drive the reduction roll units with a predetermined torque wherebyto maintain theproper tension on the stock between units.

Further objects of the improvement are set forth in the following specification which dcscribes a preferred embodiment of the invention and several modified forms of construction thereof, by way of example, as illustrated by the, accompanying drawings. In the drawings: Fig. l is a side elevational 'view of a rollin mill incorporating the novel features of the present invention;

Fig. 2 is a plan view of the rolling mill showing 'the series of sets of reduction roll and wind-up to maintain a uniform tension on and alignment of the stock between the units while the speed of the units to vary,

Another object of the invention is to provide a hydraulic drive for each of the plurality of reductlon roll units 01 a tandem mill which will maintain the pressure of the motive fluid constant for any particular adjustment.

Another object of the invention is to provide I a hydraulic drive of the type-indicated having a fluid motor and supply pump with a manually adjustable relief valve between the motor and pump for automatically bleeding the motive fluid to maintain its pressure constant.

Another object oi. the invention is to provide a rolling mill having an adjustable speed drive ior'the break-down rolls and hydraulic drives 01' the type indicated for the plurality of sets of reduction rolls.

Another object of the invention is to provide permitting I reel units arranged in tandem and the individual driving means for each unit;

, Fig. 3 is a diagrammatic view of the fluid circuits of the series of hydraulic drives showing the relief valves for controlling the pressure of the motive fluid in each circuit;

Fig. '4 is a transverse sectional view taken 'on line 4-4 of Fig. 2 showing the mounting for the edger rolls to adapt them for adjustment; f

Fig. 5 is adiagrammatic view of the fluid cir-V cuit of a modified form of hydraulic'drive for the take-up reel showing control means for automatically adjusting the displacement of a variable displacement fluid motor in accordance with the increase in the effective diameter of the reelas the stock winds'up thereon;

. Fig. 6 is a diagrammatic view of the fluid circuit of another modified form of hydraulic drive for the take-up reel showing a different form of individual hydraulic drives.

i Fig. 8 is a diagrammatic view of the fluid circuit of a hydraulic drive and control means for relatively traversing the reel and stock showing the relationship of the parts during traverse in one direction; and.

Fig. 9 is a view similar to Fig. 8 showing the relative positions of the parts during traverse in the opposite direction at a later stage in the winding operation.

The present invention relates in general to a method of and means for driving each of the units of a tandem rolling mill to maintain a substantially constant tension on the stock between adjacent sets of reduction rolls and between the last set of rolls and the take-up reel. The method consists in driving the first set of reduction rolls with a variable speed drive which may be manually adjusted to control the speed of the stock feeding through the mill, and driving the successive sets of reduction rolls with a predetermined constant torque slightly in excess of the rolling eifort whereby a substantially constant tension is maintained between adjacent sets of reduction rolls and the speed of the reduction rolls is permitted to vary to automatically adjust itself to the speed of the stock.

The rolling mill to which the present improved method is applied comprises a set of break-down rolls, a plurality of sets of reduction rolls and a take-up reel arranged in tandem to act on a single continuous strip of stock. The break-down rolls are directly driven by a variable speed primemover which controls the speed of the stock through the rolling mill. The plurality of sets of reduction rolls and take-up reels are-operated by The fluid motors of the individual hydraulic drives for the reduction rolls are responsive to the pressure of the motive fluid to drive the rolls with a predetermined cons'tant torque, and manually operated relief valves are provided in the fluid circuits for controlling the pressure of the motive fluid. The relief valves of the individual hydraulic drives are adjusted to cause. the sets of reduction rolls to apply a psedetermined constant torque slightly in excess of the rolling effort whereby the speed of the rolls adjusts itself to the speed of the stock and maintains a predetermined tension on the stock between the sets of reduction rolls and between the last set of rolls and the take-up reel. Preferably, the hydraulic drive for the take-up reelcomprises a constant horsepower fluid motor with control means for gradually varying its displacement or the amount of fluid supplied thereto to decrease the angular speed of the reel in proportion to the increase in the diameter of the layers of stock wound thereon whereby to maintain a uniform tension on the stock throughout the winding.- The invention also contemplates the use of hydraulic driving means for relatively traversin illustrated. The break-down rolls 3 are journaled one above the other in suitable bearings in the frame 2 and so arranged as to adapt them to be adjusted toward and away from each other by the hand-wheel 6 and reduction gearing 7 as will be understood by those skilled in the art. The opposite break-down rolls 3 are geared to each other and driven by a drive-shaft 8.

The edger rolls 4 are arranged in laterally spaced relationship for rotation about vertical axes and are mounted and driven in a novel manner to adapt themfor relative adjustment, as illustrated in Figs. 2 and 4. The edger rolls 4 are keyed to shafts Ill journaled at opposite sides of the frame 2 in anti-friction bearings ll carried by bearing-blocks l2. The bearing-blocks l2 for the opposite edger rolls 4 areslidable in of the screws causes sliding movement of the blocks on the ways 13. For simultaneously rotating the screws I4 a ear I! pinned to each screw meshes with pinions 18 on a shaft l9 extending parallel to the axes of the screws and having a hand-wheel 20 at one end. Thus the edger rolls 4 maybe adjusted toward or away from each other by turning the hand-wheeL 20 to rotate the shaft 13.

The edger rolls 4 are driven in any position of adjustment by means of face gears 24 on the projecting ends of the shafts ill which mesh with pinion gears 25, on a drive shaft 26. The drive shaft 26 is journaled in suitable hearings in the frame 2 and arranged transversely of the axes of the roll-shafts l0, the piniongears being made sufficiently extended to adapt the face gears 24 to slide therealong and mesh therewith in any position of adjustment.

The finishing rolls 5 are similar to the breakdown rolls 3, being arranged one above the other, geared to each other and driven by a drive shaft 21 through reduction gearing 28, see Fig. 1.

A take-up reel 30 is provided at the delivery, end of .the mill, being arranged in tandem with the break-down rolls 3 and reducing rolls 4 and 5 to wind up the rolled stock. As herein illustrated the take-up reel 30 is provided as a separate unit,

' but it will be understood that it may be constructed as an integral part of the rolling mill. As illustrated in Figs. 1 and 2 the-take-up reel 30 comprises a frame 3| having a shaft 32 journaled therein with one end extending outwardly from the frame and mounting a drum 33 on which the stock is wound. The drum 33 maybe removable from the-shaft 32 together with a roll of the finished stock thereon or it may be rigidly attached to the shaft and provided with peripheral grooves to adapt wires to be placed around the coil of wound stock to bind it for removal from the drum. The shaft 32 has a worm-wheel 34 keyed thereto which meshes with a worm 35 on a drive shaft 36.

The break-down rolls 3 are directly connected to a prime mover 39 through a coupling 40. Although the prime mover 39 may take other forms it is preferably a direct current, variable speed, electric motor. By adjusting suitable resistances and load conditions the speed of the break-down rolls can be regulated through a wide range and when once adjusted their speed determines the speed of the stock through the rolling mill. The sets of edger rolls 4, finishin rolls 5 and the take up reel 30 are operated from a second primemover 4] through individual hydraulic drives.

- closing thev separate circuits for the motors to adapt the reduction roll and take-up reel units to be simultaneously started and stopped to thread the stock through the individual units at the beginning of a rolling operation, see Fig. 3.

The hydraulic drive for the edger rolls 4 comprises a pump 45 driven by one of the shaft extensions of the electric motor 4| and a fluid motor 46 connected to the drive shaft 26 for the edger rolls through a coupling 41. The pump 45 draws motive fluid through an intake manifold 46 connected to a supply tank 49 and discharges it under pressure to a conduit connecting the pump and motor 46. The motive fluid is discharged from the fluid motor 46 through an exhaust manifold 5| which, through a conduit 52, returns the motive fluid to the tank 49.

The hydraulic drives for the finishing. rolls 5 and take-up reel are identical with that described for the edger rolls 4, comprising pumps 53 and 54 driven from one or the other of the shaft extensions of the motor 4| and drawing the motive fluid through the intake manifold 48 and discharging it under pressure through conduits 55 and 56 to fluid motors 51 and 56. The motive fluid is discharged from the motors 51 and 56 pumps 45, 53 and 54 may be of any suitable positive-displacement construction, such as gear or vane type, or of any type having a low pulsation characteristic for supplying a constant quantity of the' motive fluid. The fluid motors 46, 51 and 58 may be of any suitable type of low pulsation characteristics whereby to develop a driving torque proportional to the pressure of the motive fluid. To adapt the edger rolls 4,. finishing rolls 5 and the take-up reel 30 each to be driven with a predetermined torque, relief valves 6|, 62 and 63 are provided in the individual hydraulic drives for governing the pressure of the motive fluid therein. As illustrated in the drawings, the manually adjustable relief valves 6|, 62 and 63 are arranged-in branch conduits 64, 65. and-66 connecting the high pressure conduits 50, 55 and 56 with the exhaust manifold 5|. The relief valves may be of any suitable type for maintaining a erally similar to that shown and described in de- M tail in United States Letters Patent toCharles M.

Terry, No. 1,863,075, issued June 14, 1932. As each of the relief valves 6|, 62 and 63 is independently adjustable the pressure of the motive fluid in the hydraulic drives may be controlled individually whereby to drive the edger rolls 4, finishing rolls 5 and the take-up reel 30 with predetermined constant torques slightly in excess of the rolling or winding en'ort, as the case may be, to adapt them to accommodate theirspeed to the speed of the stock while maintaining the tension on the stock between the units substantially constant throughout a rolling operation.

One embodiment of a rolling mill incorporating the present invention having been described in detail, the mode of operation of the complete mill is as next explained.

The break-down rolls 3, edger rolls 4 and flnishing rolls 5 are first adjusted to give the proper successive reduction in the stock and the relief valves 6|, 62 and 63 are screwed down tightly to provide a maximum pressure of the motive fluid supplied to the fluid motors 46, 51 and 58 whereby to drive the reduction rolls and the wind-up reel units with a maximumtorque:

The stock is then threaded through the setof break-down rolls 3, edger rolls '4 and finishing" rolls 5 by intermittently starting and Stopping the electric motors 39' and 4| bymeans of the switch 42 and the end of the stock is attached to the drum 33 of the take-up reel 30.

The mill is thenready for a rolling operation and the speed of the stock through the mill is 1 controlled, by the adjustment of the variable speed motor 39 for driving the break-down rolls connected to the drive shafts 26, 21 and 36 and conduits 50, 55 and 56 connecting the respective pumps and motors. The pumps 45, 53 and 54 supply the motive fluid under pressure to the motors 46, 51 and 58 and the latter, being of a type in vwhich the torque developed is directly proportional to the pressure of the motive fluid, they drive their respective reduction roll and take-up reel units with a predetermined constant torque corresponding to the setting of the relief valves.

After the mill has been started the relief valve 6| in the branch conduit 64 connecting the high pressure conduit and exhaust manifold 5| of the hydraulic drive for the edger rolls 4 is turned manually to adjust the pressure of the motive fluid to a value at which the edger rolls 4 are driven with a torque only slightly in excess of therolling effort. To this end the relief valve 6| is adjusted gradually to reduce the pressure of the motive fluid in the conduit 50 untilslac'k appears in the stock between the break-down rolls 3 and edger rolls 4. The relief valve 6| is then adjusted in the opposite direction with a. predetermined slight increment of movement to increase the pressure of the motive fluid to a value at which the motor will drive the edger rolls 4 with a constant torque slightly in excess of the rolling effort to produce a predetermined tension in the stock between the break-down rolls 3 and edger rolls 4.

The relief valves 62 and 63 are also adjusted in the same manner as explained with respect to i the relief valve 6| to drive the finishing rolls 5 and the take-up reel 30 with a torque slightly in excess of the rolling or winding effort to produce a predetermined constant tension on the stock between units; 'As the fluid motors 46, 51! -and 58 drive the edger rolls 4, finishing rolls 5 and the take-upreel 30 with a predetermined constant torque the speed'of the units may vary without affecting the adjustment of the units orthe tension of the stock between units. Stated otherwise, the individual hydraulic drives for the separate units of the rolling mill may be adjusted in accordance with the present invention to vary the torque of the reduction roll and the wind-up reel units whereby numerous advantages result including convenient and quick adjustment of the units and the maintenance of a tension on the stock between units.

Although the hydraulic drive for the take-up reel 30 is shown in Figs. 1 to 4 as of the same type as that used on the edger rolls 4 and finishing rolls 5 the tension on the stock between the finishing rolls and reel will decrease slightly during a winding operation due to the increase in diameter of the superimposed layers of stock on the drum as it iswound thereon. In other words,

the hydraulic drive for the take-up reel 3!] Opelates to. drive the reel drum 33' with a constant torque, which isthe product of the moment arm and force applied, whereby any increase in the diameter of the layers of the stock or the moment arm of the reel drum due to the winding of the stock thereon causes the force or tension onthe 'ment fluid 'motor69. The pump 68 draws the motive fluid from a tank and delivers it through a, conduit 1| to the fluid motor 69, the latter dischargingthe motive fluid through the exhaust conduit I2 back to the tank 10. The fluid motor 69 may be of any suitable type such as illustrated and described in United States Letters Patent to Walter Ernst, No. 2,021,353, issued November 19, 1935. Suffice it to state herein that the displacement 01 such a. fluid motor 69 may be varied from zero to its maximum by relatively shifting its rotor laterally. In the patented constructionshift-rods are provided for relatively shiftingthe rotor while in the present construction a piston 13 is provided atone side of the rotor for shifting it laterally in one direction and a spring 14 is provided at the opposite side of the rotor opposing the action of the piston and operativ to shift the rotor laterally in the .opposite direction. With such a variable displacement motor. 69 the horsepower developed is directly dependent upon the amount and pressure of the motive fluid passing therethrough and the speed of'the motor is dependent upon the relative position of its rotor. The piston 13 is connected to the. high pressure conduit H through'an adjustable bleeding reliefv valve and. conduit 76 whereby fluid under pressure escapingftlirough j the relief valve and conduit operates the piston to increase the displacement bf the motorto de-. crease its angular speed. -As the amount of motive fluid bleeding through the relief valve 15 and conduit 16 is relatively small it will not materially aifect the amount of motive fluidpassing through the motor and the-pressureof thefluid will be maintained substantially constant by continually adjusting the displacement of the motor whereby .to maintain a constant horsepower The'speed of the motor as is controlled by the speed of the stock through the mill. If the displacement of the motor 69 is so adjusted that I the reli fgvalvelwh v it tends to operate at a higher speed the momentary resistance offered by the stock is transmitted back through the motor to increase the pressure of the motive fluid. Such instantaneous increase in the pressure of the motive fluid causes it to escape through the bleeding relief valve 15 and conduit 16 and operate the piston 13 to increase the displacement of the motor and thereby decreases its speed. The conduit 16 and piston 13 are so constructed as to permit the motive fluid bledthrough the relief valve 15 to gradually leak or escap whereby the motive fluid is continuously bled and its instantaneous pressure determines the instantaneous adjustment of the motor. As

I the diameter or moment arm of the reel drum 33 increases due to the winding of the stock thereon the displacement of the motor is increased automatically to decrease its angular speed without varying the amount or pressure of the motive fluid, the decrease in speed being in direct proportion to the increase in the moment arm to maintain a constant tension on the stock. In other words, the motor develops a constant horsepower but its displacement and speed is continuously and automatically controlled to maintain a constant tension on the stock.

In Fig. 6 another form of constant horsepower hydraulic drive for the take-up reel 38 is illustrated in which the relationship of the pressure and amount of motive fluid passing through the motor are automatically controlled to maintain a constant tension on the stock. This form of hydraulic drive comprises a constant displacement fluid pump '18 and constant displacement fluid motor 19 connected in the same manner as a the pump and motor illustrated in Fig. 5. An adprises a ball 84 yieldingly pressed against a valve seat 85 by a compression spring 86. The com- I -pression or resistance of the spring 86 is adjusted by a slidable block 81 having a stem 88 projecting upwardly through the valve casing. A lever 89 pivoted intermediate its ends has one end bearing against the-end of the valve-stem 88 and a feeler 90 atits opposit end bearing against the stock being wound on thereel drum 33.

Without any control means the-speed of the constant displacement; motor-J9 depends upon the amount of motive fluid passing therethrough and the horsepower is dependent upon the; amount and pressure of the motive fluid passing therethrough. ,To decrease the speed of thefluid motor 19 to compensate forfthe increase in diameter of'the stock wi'n'dingo'n the reel drum 83 part of' the motive-fluid must be bled through H H Si'the speedof stock controls the speed of theflui'd motor; s the instantaneous 1 resistancei '11 ause the fluid .to escapeythrou'gh power of 'the motor'must be maintained constant by increasing the pressure of the motive fluid.

Duringthe winding of the stock on the reel drum 33 the lever 89 is rocked on its pivot to increase the compression of the'spring 86in pro-- conduit 82- to'mainta'in a constant horsepower asthe speed of the fluid-motor decreases.' In other take-up reel 30. In this form of hydraulic drive a variable displacement pump 92 is rovided of the same type as the fluid motor 69 illustrated in Fig. 5. The fluid motor 93 is'of a constant displacement type whereby its speed and the speed of the reel drum 3-3 connected thereto is dependent upon the amount of motive fluid passing therethrough and the horsepower is depend ent upon the amount and pressure of the fluid passing therethrough. The piston 94 for adjusting the displacement of the pump 92 is connected to the high pressure conduit 95 through a branch conduit 96. A spring 9! at the opposite side of the pump '92 opposes the action of the piston 94. The motive fluid exhausting from the fluid motor 93 discharges into a'supply tank 99 from which it is drawn to the pump 92.

With this latter form 01 hydraulic drive for the take-up reel 30 the pump 92 supplies a predetermined amount of motive fluid to drive the fluid motor 93 at the same speed as the'stock to apply a predetermined tension thereon. As the stock winding on the reel drum 33 increases 'in diameter the tension on the stock is transmitted back through the fluid motor 93 to cause an instantaneous increasedn the pressure of the H2 and discharging it through a conduit H3. The motive fluid passes through an adjustable metering box or valve H4 in the conduit H3 which controls the amount of motive fluid passing therethrough at a predetermined pressure and the pressure of the fluid in the conduit is controlled by the bleeding relief valve H5 which discharges surplus motive fluid through the conduit H6 back to the tank H2. The metering valve H4 may be of any suitable type such as that illustrated and described in United States Letters Patent to T. L. Farnham, No. 2,146,537, issued February 7, 1939. The motive fluid passing through the metering valve H4 enters'the casing H8 of a two-way valve through an inlet port III. A valve plug or septum H9 in the valve casing H8 in one position of adjustment connects the inlet port III with a port I20 connected by a conduit I2I to the cylinder 105 at one side of the piston I06. By turning the valve plug H9 from the position shown in Fig. 8 to that shown in Fig. 9 the inlet port III. of the valve casing is connected to a port I22 which directs the motive fluid through a conduit I23 to the cylinder I05 at the opposite side of the piston I06. The ports I20 and I22 are also alternatelyconnected to an exhaust port I24 in the valve casing H8 as the valve plug is rocked from one to the other of its motive fluid which, acting through the branch 1 of the motor to maintain a constant horsepower and thereby a constant tension on "the stock.

'In other words, the gradual increase in the compression of the spring 91 efl'ects a gradual increase in the pressure of the motive fluid to compensate for the decrease in the amount of fluid supplied by the pump 92 to maintain a constant horsepower.

The present invention alsocontemplates hydraulic driving means for relatively traversing the take-up reel and stock to wind the latter in superimposed layersoi closely adjacent coils as illustrated in Figs. 8 and 9. In this form of drive the take-up drum I00 of the reel. is mounted on the end of a shaft IOI-adapteddor sliding movement. The shaft MI is driven by a worm-wheel I02 which, in turn, is driven by a worm I03, the shaft being provided with a spline I04 to adapt it for longitudinal sliding movement with respect to the worm-wheel. The opposite end of the shaft I 0I extends into a cylinder I05 and has a piston I06 at its end.

Motive fluid is supplied to the cylinder I05 alternately at one side and then at the other of the piston I06 to cause reciprocation'oi the shaft IOI and :take-up reel'drum I00 mounted thereon. The fluid circuit for the cylinder I05 comprises a pump H0 driven by an electric motor III, the pump drawing motive fluid from a tank two positions illustrated in Figs. 8 and 9 so that the motive fluid is exhausted from one end of the cylinder I05 as it is being supplied to the other side. The exhaust port I24 is connected b a conduit I25 to the tank H2. r i

A snap-acting mechanism is provided for operating the valve plug H9 at the end of the stroke of the piston I06 and take-up reel drum I00. The snap-acting mechanism herein illustrated comprises a lever I28 pivoted intermediate its ends at I29 with one end pivotally connected to an operating arm I30 of the valve plug I I9. A second lever I3I is pivotally connected at one end to the lever I28 intermediate the pivot I29 and the end connected to the operating arm I30 and its opposite end I32 is bifuricated to embrace the shaft 'I9I between spaced stops 133 and I34 on the latter. The lever 'I3I and the end of the to the left as'viewed in Fig. 8 the stop I34 act-j lever I29 opposite from the one connected to the valve operating arm I30 are connected by an over-center compression spring I35. 7

Thus, as the shaft IM and reel drum I00 move ing on the bifurcated end I32of the lever I3I rocks the latter to the position illustrated in dash-lines in Fig. 8. The lower end of the spring I35 having been moved beyond the center line of the lever I28 causes the spring to act on the lower end of said lever to rock it to the position illustrated in Fig. 9. Thus the upper end of the lever I29 is moved to the left as viewed in Fig. 9 and, due to its pivotal connection with the operating arm I30 of the valve plug H9 it rocks, the latter with a snap action from the position shown in Fig; 8 to that illustrated in Fig. 9. The hydraulic driving means is thus operative to relatively traverse the reel drum I00 and stock first inone direction and thenin the other to lay the stock in superimposed layers of closely adjacent coils. the control valve H9 being automatically operated 'to reverse the direction of traverse at the end-of each stroke. a As the layers of-stock build up on the reel drum I00 a greater length of stock is wound at each revolution of the drum. I00. To ome pensate tor the increase in diameter of the layers of stock on the reel drum III!) as the stock is wound thereon it is desirable to slowly diminish the rate of traverse of the drum and stock to cause the latter to be laid in closely adjacent coils throughout the winding. To this end a lever I38 pivoted intermediate its ends at I40 has a feeler projection or roller I at one end for engagement with the stock on the reel I00. The opposite end of the lever I38 is connected to an adjusting arm I42 of the metering box II4 through a link l43. Thus, as the diameter of the stock winding on the reel I increases the lever I38 is rocked in a counterclockwise direction and acting through the link I43 it operates the adjusting arm I42 of the metering box in direct proportion to the increase in diameter of the stock on the reel to decrease the amount of motive fluid flowing to the cylinder I and thereby diminish the speed of relative traverse of the drum I00 andthe stock.

It will be observed from the foregoing specification that the present invention provides individual hydraulic drives for the several units of a rolling mill for operating the reduction rolls with a predetermined constant torque slightly in excess of the rolling effort to maintain a tension on the stock between units while permitting the speed of the reduction rolls to vary in accordance with the linear speed of the stock. It will be observed further that th invention provides a constant horsepower hydraulic drive for the take-up reel which is self-adjustingto decrease the angular velocity of the reel in proportion to the .increase in diameter of the layers of stock winding on the reel. It will .be observed still furtherthat the present invention contemplates hydraulic driving means for relatively traversing the reel and stock to wind the latter in superimposed layers of closely adjacent coils with automatically operated'means for decreasing the rate of traverse in proportion to the increase in diameter of the layers of stock wound on the reel drum.

While a preferred and several modified forms of hydraulic drives for the individual units of a rolling mill are herein illustrated and described, it will be understood that further modifications may be made in the form and arrangement of the hydraulic drives and in the construction of the units of the rolling mill with which they are used without departing from the spirit or scope of the invention. For example, a pressure controlled variable displacement pump may be used in the hydraulic circuit in place of the constant displacement pump and relief valve illustrated in the drawings to maintain the pressure of the motive fluid constant. Therefore, without limiting ourselves in this respect, we claim:

1. The method of rolling stock in a tandem rolling mill which comprises driving eachset of reduction rolls with a predetermined constant torque and permitting the speed of said reduction rolls to vary to automatically adjust itself to the speed of the stock. a

2. The method of rolling stock in a tandem rolling mill which comprises driving each set of reduction rolls with a predetermined constant torque slightly in excess of the rolling effort while permitting the speed of the rolls to var whereby said reduction rolls automatically adjust their speed to the speed of the stock .passing there-- between.

3. The method of rolling stock in a tandem rolling mill having a series of sets of reduction rolls which comprises driving each of the plurality of sets of reduction rolls with a predetermined constant torque slightly in excess of the rolling efiort tomaintain a tension between the sets of reduction rolls while permitting the speed of the reduction rolls to vary and automatically adjust itself to the speed of the stock.

4. The method of rolling stock in a tandem rolling mill having a set of break-down rolls and a plurality of sets of reduction rolls which comprises driving the break-down rolls with an adjustable speed drive to adapt the speed of the stock through the mill to be manually controlled, and driving each set of reduction rolls with a predetermined constant torque slightly in excess of the rolling eifort while permitting the speed of the reduction rolls to vary to automatically adjust itself to the speed of the stock.

5. The method of rolling stock in a tandem rolling mill having a plurality of sets of reduction rolls and a take-up reel which comprises driving each set of reduction rolls with a predetermined constant torque slightly in excess of the rolling efiort to tension the stock between V the sets of reduction rolls, and driving the takeup reel with a constant horsepower flexible drive to maintain a. constant tension on the stock between the last set of reduction rolls and the take-up reel during the winding of the stock on the latter.

6. In a rolling mill, a set of reduction rolls, a hydraulic drive for operating said reduction rolls, and meansfor controlling the motive fluid of the hydraulic drive to maintain its pressure constant during a rolling operation whereby the torque applied to said reduction rolls by said hydraulic drive is maintained substantially .con- 'stant at any speed of the reduction rolls.

7. In'a rolling mill, 2. set of reduction rolls, a hydraulic motor for driving said reduction rolls, a pump for supplying motive fluid to said motor, and an adjustable pressure-responsive relief valve between the motor and said pump for controlling the motive fluid supplied to said motorto maintain a predetermined constant pressure at any particular adjustmentduring a rolling operation whereby the torque applied to the reduction rolls by said hydraulic drive is maintained substantially constant and the speed of the reduction rolls is permitted to vary.

8. In a rolling mill, a plurality of' sets of reduction rolls arranged in tandem for simultaneously acting upon a continuous length of stock, an individual hydraulic drive for each set of reduction rolls, and ,means for independently controlling the motive fluid of each hydraulic drive to maintain its pressure constant during a rolling operation whereby the torque applied to each set of reduction rolls by its hydraulic drive is maintained substantially constant while permitting the speed of the reduction rolls to' vary to adjust themselvesto the linear speed of the tive fluid supplied to each of said hydraulic motors to' maintain its pressure constant during a rolling operation whereby the torque applied to each set of reduction rolls by its hydraulic drive is maintained substantially constant and slightly in excess of the rolling efiort.

10. In a rolling mill, a plurality of sets or reduction rolls arranged in tandem for simultaneously acting'upon a, continuous length of stock, an individual hydraulic drive for each of certain of the sets,of reduction rolls comprising a fluid motor and a pump for supplying motive fluid under pressure thereto, and an adjustable relief valve in each hydraulic drive for controlling the motive fluid to maintain a predetermined constant pressure at any particular adjustment during a rolling operation whereby to maintain the torque applied to each set of reduction rolls slightly in excess of the rolling effort while permitting the reduction rolls to automatically adjust their speed to the linear speed of the stock I passing therebetween.

11. In a rolling mill, a set of break-down rolls, a plurality of sets or reduction rolls, said breakdown rolls and plurality of sets of reduction rolls being arrangedin tandem to simultaneously act upon continuous length of stock, an adjustable speed motor for driving the set 01 break-down rolls, an individual lwdraulic drive for each of the sets or reduction rolls. and means for independently controlling the motive fluid for each hydraulic drive to maintain its pressure constant during a rolling operation whereby to individually maintain a predetermined constant a plurality of sets of reduction rolls, said breakdown rolls and plurality of sets of reduction rolls being arranged in tandem to simultaneously act upon a continuous length 01' stock, an adjustable speed motor for driving the set of break-down rolls, a fluid motor for each set of reduction rolls, a pump for each .flui'd motor connected thereto for supplying motive fluid under pressure, and a manually adjustable relief valve between the pump and motor of each hydraulic unit for individually controlling the pressure of the motive fluid and the torque ap-- plied to each set of reduction rolls by its hydraulic drive. said relief valve maintaining the pressure of the motive fluid and torque substantially constant at any particular setting.

13. In a rolling mill, 9. set of break-down rolls, a plurality of sets of reduction rolls, said set of break-down rolls and plurality of sets of reduction rolls being arranged in tandem to simultaneously act upon a continuous length of. stock,

an adjustable speed electric motor for driving the set of break-down rolls, a fluid motor for each set of reduction rolls, a pump for each fluid motor connected thereto for supplying motive fluid under pressure, a constant speed electric motor for simultaneously driving the plurality of pumps, and a manually adjustable reliet valve between the pump and motor of each hydraulic unit to individually control the pressure'ot the motive fluid and the torque applied to each set of reduction rolls by its hydraulic drive.

14. In a rolling mill, a plurality of sets or reduction rolls, a take-up reel, said reduction rolls and take-up reel being arranged in tandem to simultaneously act upon a continuous length 01' stock and wind the rolled stock on the reel, an, individual hydraulic drive for each of certain of the sets of reduction rolls and the take-up reel,

and means for controlling the motive fluid of 5 vary whereby to maintain a constant torque ap-' plied to each set of reduction rolls andlto the take-up reel by its hydraulic drive while permitting the sets of reduction rolls and the take-up reel ,to automatically adjust their speed. to the speed of the stock.

15. In a rolling mill, a set of break-down rolls, a plurality of sets of reduction rolls, a take-up reel, said break-down rolls, reductionirolls and take-up reel being arranged in tandem to simultaneously act upon a continuous length of stock, an adjustable speed electric motor for driving the set of break-down rolls, an individual hydraulic drive for each set of reduction rolls and the take-up reel, and means for independently controlling the motive fluid in each hydraulicv drive to maintain its pressure constant during arolling operation whereby to individually maintain a constant torque applied to each setof reduction rolls and to the take-up reel by its hydraulic drive.

16. In a rolling a plurality of'sets of reduction rolls, a take-up reel, said sets of reduction rolls and take-up reel being arranged. in tandem to simultaneously act upon a continuous length of stock' and wind the rolled stock on the reel, an individual hydraulic drive for each' set of reduction rolls and for the take-up reel, means -for controlling each of the hydraulic drives for the reduction rolls to maintain a constant torque applied to the reduction rolls slightly in excess of the rolling eifort, and means for controlling the hydraulic drive for the 'take u'p reel to gradually decrease the angular velocity of the reel in proportion to the increase in diameter.

of the layers of stock wound thereon while maintainlng a constant tension on the stock.

17. In a rolling mill, a pluralityof sets of reduction rolls, a take-up reel, said sets oi? reduction rolls and take-up reel being arranged in tandem tosimultaneously act upon a continuous length of stock and wind the rolled stock on the reel, individual hydraulic drives for the separate sets of reduction rolls and the take-up reel, said go-hydraulic drives for the reduction rolls having constant displacement inotors responsive to the pressure or the motive fluid and adjustable relief valves for maintaining the pressure of the fluid constant for any particular adjustment, said 5 hydraulic drive .for the take -up reel having a variable displacementmotor in which the speed varies in proportion to the displacement, and means for controlling the displacement of the motor oi the hydraulic drive for the take-up reel to gradually decrease the angular velocity of the latter in proportion to the increase in diameter of the layers of stock wound thereon while maintaining a'constant tension on the stock.

'18-. In a rolling mill, a set of reduction rolls, a hydraulic drive for operating at least one of said reduction rolls, means for controlling the motive fluid of the hydraulic drive to maintain its pressure constant during a rolling operation whereby the torque applied to saidreduction roll by said 7 drive is maintained substantially constant at any speed of the reduction roll.

' Y CHRISTIAN E. GROSSER.

HERMAN A. BONDESON. 

